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LT1170/LT1171/LT1172
100kHz, 5A, 2.5A and 1.25AHigh Efficiency Switching Regulators
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ESCRIPTIOSFEATURE Wide Input Voltage Range: 3V to 60V Low Quiescent Current: 6mA Internal 5A Switch (2.5A for LT1171,
1.25A for LT1172) Very Few External Parts Required Self-Protected Against Overloads Operates in Nearly All Switching Topologies Shutdown Mode Draws Only 50µA Supply Current Flyback-Regulated Mode Has Fully Floating Outputs Comes in Standard 5-Pin Packages LT1172 Available in 8-Pin MiniDIP and Surface Mount
Packages Can Be Externally Synchronized
The LT®1170/LT1171/LT1172 are monolithic high powerswitching regulators. They can be operated in all standardswitching configurations including buck, boost, flyback,forward, inverting and “Cuk.” A high current, high effi-ciency switch is included on the die along with all oscilla-tor, control and protection circuitry. Integration of allfunctions allows the LT1170/LT1171/LT1172 to be built ina standard 5-pin TO-3 or TO-220 power package as well asthe 8-pin packages (LT1172). This makes them extremelyeasy to use and provides “bust proof” operation similar tothat obtained with 3-pin linear regulators.
The LT1170/LT1171/LT1172 operate with supply volt-ages from 3V to 60V, and draw only 6mA quiescentcurrent. They can deliver load power up to 100W with noexternal power devices. By utilizing current-mode switch-ing techniques, they provide excellent AC and DC load andline regulation.
The LT1170/LT1171/LT1172 have many unique featuresnot found even on the vastly more difficult to use lowpower control chips presently available. They use adaptiveantisat switch drive to allow very wide ranging load cur-rents with no loss in efficiency. An externally activatedshutdown mode reduces total supply current to 50µAtypically for standby operation.
Boost Converter (5V to 12V)
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PPLICATITYPICALMaximum Output Power*
INPUT VOLTAGE (V)0
POW
ER (W
) **
100
80
60
40
20
040
LT1170/1/2 TA02
10 20 30 50
*ROUGH GUIDE ONLY. BUCK MODE P OUT = (5A)(VOUT) SPECIAL TOPOLOGIES DELIVER MORE POWER. **DIVIDE VERTICAL POWER SCALE BY TWO FOR LT1171, BY FOUR FOR LT1172.
BOOST
BUCK-BOOST VO = 30V
FLYBACK
BUCK-BOOST VO = 5V
LT1170
, LTC and LT are registered trademarks of Linear Technology Corporation.
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PPLICATI Logic Supply 5V at 10A 5V Logic to ±15V Op Amp Supply Battery Upconverter Power Inverter (+ to –) or (– to +) Fully Floating Multiple OutputsUSER NOTE:This data sheet is only intended to provide specifications, graphs, and a general functional descriptionof the LT1170/LT1171/LT1172. Application circuits are included to show the capability of theLT1170/LT1171/LT1172. A complete design manual (AN19) should be obtained to assist indeveloping new designs. This manual contains a comprehensive discussion of both the LT1070 andthe external components used with it, as well as complete formulas for calculating the values of thesecomponents. The manual can also be used for the LT1170/LT1171/LT1172 by factoring in the higherfrequency. A CAD design program called SwitcherCADTM is also available.
1170/1/2 TA01
D1 MBR330
C2 1000µF+
C1 1µF
R1 10.7k 1%
R2 1.24k 1%
L1**50µH
LT1170
GND
VIN
5V
R3 1k
*REQUIRED IF INPUT LEADS ≥ 2" ** COILTRONICS 50-2-52 PULSE ENGINEERING 92114
VSW
FBVC
+
OUTPUT FILTER
L2 10µH
C3 100µF
12V 1A
C3* 100µF
SwitcherCAD is a trademark of Linear Technology Corporation.
2
LT1170/LT1171/LT1172
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A
W
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ARBSOLUTE XI TI S
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PACKAGE/ORDER I FOR ATIOSupply Voltage
LT1170/71/72HV ................................................ 60VLT1170/71/72 (See Note 1) ................................ 40V
Switch Output VoltageLT1170/71/72HV ................................................ 75VLT1170/71/72 ..................................................... 65VLT1172S8 ........................................................... 60V
Feedback Pin Voltage (Transient, 1ms) ................ ±15VStorage Temperature Range ............... –65°C to 150°CLead Temperature (Soldering, 10 sec)................. 300°COperating Junction Temperature Range
LT1170/71/72M............................... –55°C to 150°CLT1170/71/72HVC,
LT1170/71/72C (Oper.) .................... 0°C to 100°CLT1170/71/72HVC,
LT1170/71/72C (Sh. Ckt.) ................ 0°C to 125°CLT1170/71/72I (Oper.) .................... –40°C to 100°CLT1170/71/72I (Sh. Ckt.) ................. –40°C to 125°C
Note 1: Minimum effective switch “on” time for the LT1170/71/72 (in currentlimit only) is ≈ 0.6µs. This limits the maximum safe input voltage during anoutput shorted condition. Buck mode and inverting mode input voltage duringan output shorted condition is limited to:
VIN (max, output shorted) = 15V +buck and inverting modeR = Inductor DC resistanceIL = 10A for LT1170, 5A for LT1171, and 2.5A for LT1172Vf = Output catch diode forward voltage at ILt = 0.6µs, f = 100kHz switching frequencyMaximum input voltage can be increased by increasing R or Vf.External current limiting such as that shown in AN19, Figure 39, willprovide protection up to the full supply voltage rating. C1 in Figure 39should be reduced to 200pF.Transformer designs will tolerate much higher input voltages becauseleakage inductance limits rate of rise of current in the switch. Thesedesigns must be evaluated individually to assure that current limit is wellcontrolled up to maximum input voltage.Boost mode designs are never protected against output shorts becausethe external catch diode and inductor connect input to output.
TJMAX θJC θJALT1170CT/LT1170HVCT 100°C 2°C/W 75°C/WLT1171CT/LT1171HVCT 100°C 4°C/W 75°C/WLT1172CT/LT1172HVCT 100°C 8°C/W 75°C/WBased on continuous operation.TJMAX = 125°C for intermittent fault conditions.
(R)(IL) + Vf(t)(f)
ORDER PARTNUMBER
T PACKAGE, 5-LEAD TO-220
VIN VSW GND FB VC
FRONT VIEW 5 4 3 2 1
ORDER PARTNUMBER
LT1170CTLT1170ITLT1170HVCTLT1170HVITLT1171CTLT1171ITLT1171HVCTLT1172CTLT1172HVCT
TJMAX = 100°C, θJA = 150°C/W
TOP VIEW
SW PACKAGE, 16-LEAD PLASTIC SO WIDE
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
NC
NC
GND
VC
FB
NC
NC
NC
NC
NC
E2
VSW
E1
VIN
NC
NC
Based on continuous operation.TJMAX = 125°C for intermittent fault conditions.
LT1172CSW
ORDER PARTNUMBER
Q PACKAGE, 5-LEAD DD
VIN VSW GND FB VC
FRONT VIEW
5 4 3 2 1
*θ will vary fromapproximately 25°C/W with2.8 sq. in. of 1oz. copper to45°C/W with 0.20 sq. in. of1oz. copper. Somewhatlower values can beobtained with additionalcopper layers in multilayerboards.
TJMAX = 100°C, θJA = *°C/W
ORDER PARTNUMBER
LT1170CQLT1171CQLT1172CQ
TJMAX θJC θJALT1170MK 150°C 2°C/W 35°C/WLT1170CK 100°C 2°C/W 35°C/WLT1171MK 150°C 4°C/W 35°C/WLT1171CK 100°C 4°C/W 35°C/WLT1172MK 150°C 8°C/W 35°C/WLT1172CK 150°C 8°C/W 35°C/WBased on continuous operation.TJMAX = 125°C for intermittent fault conditions.
2
4
1
3
VSW VC
FB
CASE IS GND
VIN
K PACKAGE, 4-LEAD TO-3 METAL CAN
BOTTOM VIEW ORDER PARTNUMBER
LT1170MKLT1170CKLT1171MKLT1171CKLT1172MKLT1172CK
TJMAX = 150°C, θJA = 100°C/W (J)TJMAX = 100°C, θJA = 100°C/W (N)TJMAX = 100°C, θJA = 120°C/W to 150°C/Wdepending on board layout (S)
11721172I
S8 PART MARKING
LT1172MJ8LT1172CJ8LT1172CN8LT1172IN8LT1172CS8LT1172IS8
N8 PACKAGE 8-LEAD PDIP
1
2
3
4
8
7
6
5
TOP VIEW
GND
VC
FB
NC*
E2
VSW
E1
VIN
J8 PACKAGE 8-LEAD CERDIP
S8 PACKAGE, 8-LEAD PLASTIC SO * Do not connect Pin 4 of the LT1172 DIP or SO to external
circuitry. This pin may be active in future revisions.
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LT1170/LT1171/LT1172
ELECTRICAL C CHARA TERISTICS VIN = 15V, VC = 0.5V, VFB = VREF, output pin open, unless otherwise noted.
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
VREF Reference Voltage Measured at Feedback Pin 1.224 1.244 1.264 VVC = 0.8V 1.214 1.244 1.274 V
IB Feedback Input Current VFB = VREF 350 750 nA 1100 nA
gm Error Amplifier ∆IC = ±25µA 3000 4400 6000 µmhoTransconductance 2400 7000 µmho
Error Amplifier Source or VC = 1.5V 150 200 350 µASink Current 120 400 µA
Error Amplifier Clamp Hi Clamp, VFB = 1V 1.80 2.30 VVoltage Lo Clamp, VFB = 1.5V 0.25 0.38 0.52 V
Reference Voltage Line 3V ≤ VIN ≤ VMAX 0.03 %/VRegulation VC = 0.8V
AV Error Amplifier Voltage Gain 0.9V ≤ VC ≤ 1.4V 500 800 V/V
Minimum Input Voltage (Note 3) 2.6 3.0 V
IQ Supply Current 3V ≤ VIN ≤ VMAX, VC = 0.6V 6 9 mA
Control Pin Threshold Duty Cycle = 0 0.8 0.9 1.08 V 0.6 1.25 V
Normal/Flyback Threshold 0.4 0.45 0.54 Von Feedback Pin
VFB Flyback Reference Voltage IFB = 50µA 15.0 16.3 17.6 V(Note 3) 14.0 18.0 V
Change in Flyback Reference 0.05 ≤ IFB ≤ 1mA 4.5 6.8 9 VVoltage
Flyback Reference Voltage IFB = 50µA 0.01 0.03 %/VLine Regulation (Note 3) 7V ≤ VIN ≤ VMAX
Flyback Amplifier ∆IC = ±10µA 150 300 650 µmhoTransconductance (gm)
Flyback Amplifier Source VC = 0.6V Source 15 32 70 µAand Sink Current IFB = 50µA Sink 25 40 70 µA
BV Output Switch Breakdown 3V ≤ VIN ≤ VMAX, LT1170/LT1171/LT1172 65 90 VVoltage ISW = 1.5mA LT1170HV/LT1171HV/LT1172HV 75 90 V
LT1172S8 60 80 V
VSAT Output Switch LT1170 0.15 0.24 Ω“On” Resistance (Note 1) LT1171 0.30 0.50 Ω
LT1172 0.60 1.00 ΩControl Voltage to Switch LT1170 8 A/VCurrent Transconductance LT1171 4 A/V
LT1172 2 A/V
ILIM Switch Current Limit (LT1170) Duty Cycle = 50% TJ ≥ 25°C 5 10 ADuty Cycle = 50% TJ < 25°C 5 11 ADuty Cycle = 80% (Note 2) 4 10 A
(LT1171) Duty Cycle = 50% TJ ≥ 25°C 2.5 5.0 ADuty Cycle = 50% TJ < 25°C 2.5 5.5 ADuty Cycle = 80% (Note 2) 2.0 5.0 A
(LT1172) Duty Cycle = 50% TJ ≥ 25°C 1.25 3.0 ADuty Cycle = 50% TJ < 25°C 1.25 3.5 ADuty Cycle = 80% (Note 2) 1.00 2.5 A
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LT1170/LT1171/LT1172
ELECTRICAL C CHARA TERISTICS VIN = 15V, VC = 0.5V, VFB = VREF, output pin open, unless otherwise noted.
guaranteed switch current is given by ILIM = 3.33 (2 – DC) for the LT1170,ILIM = 1.67 (2 – DC) for the LT1171, and ILIM = 0.833 (2 – DC) for theLT1172.Note 3: Minimum input voltage for isolated flyback mode is 7V. VMAX =55V for HV grade in fully isolated mode to avoid switch breakdown.
∆IIN Supply Current Increase 25 35 mA/A∆ISW During Switch On-Time
f Switching Frequency 88 100 112 kHz 85 115 kHz
DCMAX Maximum Switch Duty Cycle 85 92 97 %
Shutdown Mode 3V ≤ VIN ≤ VMAX 100 250 µASupply Current VC = 0.05V
Shutdown Mode 3V ≤ VIN ≤ VMAX 100 150 250 mVThreshold Voltage 50 300 mV
Flyback Sense Delay Time (Note 3) 1.5 µs
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
Reference Voltage vs Temperature
INPUT VOLTAGE (V)0
REFE
RENC
E VO
LTAG
E CH
ANGE
(mV)
10 20 30 40
1170/1/2 G04
50
5
4
3
2
1
0
–1
–2
–3
–4
–560
TJ = 150°C
TJ = –55°CTJ = 25°C
Line Regulation
TEMPERATURE (°C)
REFE
RENC
E VO
LTAG
E (V
)
1170/1/2 G05
1.250
1.248
1.246
1.244
1.242
1.240
1.238
1.236
1.234–75 –25 25 50 150–50 0 75 100 125
The denotes the specifications which apply over the full operatingtemperature range.VMAX = 40V for LT1170/71/72 and 60V for LT1170/71/72HV.Note 1: Measured with VC in hi clamp, VFB = 0.8V. ISW = 4A for LT1170,2A for LT1171, and 1A for LT1172.Note 2: For duty cycles (DC) between 50% and 80%, minimum
TEMPERATURE (°C)
FEED
BACK
BIA
S CU
RREN
T (n
A)
1170/1/2 G06
800
700
600
500
400
300
200
100
0–75 –25 25 50 150–50 0 75 100 125
Feedback Bias Current vsTemperature
C CHARA TERISTICS
UW
ATYPICAL PERFOR CESwitch Current Limit vs Duty Cycle*
TEMPERATURE (°C)–75
MIN
IMUM
INPU
T VO
LTAG
E (V
)
–25 25 50 150
1170/1/2 G02
–50 0 75 100 125
2.9
2.8
2.7
2.6
2.5
2.4
2.3
SWITCH CURRENT = 0A
SWITCH CURRENT = IMAX
Minimum Input Voltage Switch Saturation Voltage
DUTY CYCLE (%)
0
SWIT
CH C
URRE
NT (A
)
16
12
8
4
040
1170/1/2 G01
20 30 50 60 70 80 90 100
25°C
125°C
–55°C
10
* DIVIDE VERTICAL SCALE BY TWO FOR LT1171, BY FOUR FOR LT1172.
SWITCH CURRENT (A)*0
SWIT
CH S
ATUR
ATIO
N VO
LTAG
E (V
)
8
1170/1/2 G03
1 2 3
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
04 5 6 7
25°C
150°C
–55°C
100°C
* DIVIDE CURRENT BY TWO FOR LT1171, BY FOUR FOR LT1172.
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LT1170/LT1171/LT1172
C CHARA TERISTICS
UW
ATYPICAL PERFOR CE
TEMPERATURE (°C)
IDLE
SUP
PLY
CURR
ENT
(mA)
11
10
9
8
7
6
5
4
3
2
1
1170/1/2 G13
–75 –25 25 50 150–50 0 75 100 125
VSUPPLY = 60V
VSUPPLY = 3V
VC = 0.6V
INPUT VOLTAGE (V)0
SUPP
LY C
URRE
NT (m
A)
10 20 30 401170/1/2 G09
50
15
14
13
12
11
10
9
8
7
6
560
TJ = 25°C NOTE THAT THIS CURRENT DOES NOT INCLUDE DRIVER CURRENT, WHICH IS A FUNCTION OF LOAD CURRENT AND DUTY CYCLE.
90% DUTY CYCLE
50% DUTY CYCLE
10% DUTY CYCLE
0% DUTY CYCLE
* UNDER VERY LOW OUTPUT CURRENT CONDITIONS, DUTY CYCLE FOR MOST CIRCUITS WILL APPROACH 10% OR LESS.
Supply Current vs Input Voltage*
Feedback Pin Clamp Voltage Switch “Off” CharacteristicsIdle Supply Current vsTemperature
VC PIN VOLTAGE (mV)0
SUPP
LY C
URRE
NT (µ
A)
200
180
160
140
120
100
80
60
40
20
040
1170/1/2 G10
10 20 30 50 60 70 80 90 100
TJ = 150°C
–55°C ≤ TJ ≤ 125°C
Shutdown Mode Supply Current
TEMPERATURE (°C)
TRAN
SCON
DUCT
ANCE
(µm
ho)
5000
4500
4000
3500
3000
2500
2000
1500
1000
500
0
1170/1/2 G11
–75 –25 25 50 150–50 0 75 100 125
gm = ∆I (VC PIN) ∆V (FB PIN)
Error Amplifier Transconductance VC Pin Characteristics
SUPPLY VOLTAGE (V)0
SUPP
LY C
URRE
NT (µ
A)
10 20 30 40
160
140
120
100
80
60
40
20
050 60
1170/1/2 G07
VC = 50mV
VC = 0V
TJ = 25°C
Supply Current vs Supply Voltage(Shutdown Mode) Driver Current* vs Switch Current
SWITCH CURRENT (A)0
DRIV
ER C
URRE
NT (m
A)
1 2 3
160
140
120
100
80
60
40
20
04 5
1170/1/2 G08
TJ = –55°C
TJ = ≥ 25°C
* AVERAGE LT1170 POWER SUPPLY CURRENT IS FOUND BY MULTIPLYING DRIVER CURRENT BY DUTY CYCLE, THEN ADDING QUIESCENT CURRENT.
VC PIN VOLTAGE (V)
300
200
100
0
–100
–200
–300
–400
1170/1/2 G12
V C P
IN C
URRE
NT (µ
A)
0 2.00.5 1.0 1.5 2.5
VFB = 1.5V (CURRENT INTO VC PIN)
VFB = 0.8V (CURRENT OUT OF VC PIN)
TJ = 25°C
FEEDBACK CURRENT (mA)0
FEED
BACK
VOL
TAGE
(mV)
500
450
400
350
300
250
200
150
100
50
00.4
1170/1/2 G14
0.1 0.2 0.3 0.5 0.6 0.7 0.8 0.9 1.0
–55°C
25°C
150°C
SWITCH VOLTAGE (V)0
SWIT
CH C
URRE
NT (µ
A)
1000
900
800
700
600
500
400
300
200
100
040
1170/1/2 G15
10 20 30 50 60 70 80 90 100
VSUPPLY = 55V
VSUPPLY = 3V
VSUPPLY = 15V
VSUPPLY = 40V
6
LT1170/LT1171/LT1172
C CHARA TERISTICS
UW
ATYPICAL PERFOR CE
TEMPERATURE (°C)
V C P
IN V
OLTA
GE (m
V)
1170/1/2 G16
400
350
300
250
200
150
100
50
0–75 –25 25 50 150–50 0 75 100 125
–400
–350
–300
–250
–200
–150
–100
–50
0
VC PIN CURRENT (µA)
CURRENT (OUT OF VC PIN)
VOLTAGE
VC VOLTAGE IS REDUCED UNTIL REGULATOR CURRENT DROPS BELOW 300µA
JUNCTION TEMPERATURE (°C)–75
TIM
E (µ
s)
–25 25 50 150
1170/1/2 G17
–50 0 75 100 125
2.2
2.0
1.8
1.6
1.4
1.2
1.0
Isolated Mode Flyback ReferenceVoltage
TEMPERATURE (°C)
FLYB
ACK
VOLT
AGE
(V)
1170/1/2 G18
23
22
21
20
19
18
17
16
15–75 –25 25 50 150–50 0 75 100 125
RFB = 500Ω
RFB = 1k
RFB = 10k
Normal/Flyback Mode Threshold onFeedback Pin
TEMPERATURE (°C)–50
FEED
BACK
PIN
VOL
TAGE
(mV)
500
490
480
470
460
450
440
430
420
410
4000 50 75
1170/1/2 G20
–25 25 100 125 150
–24
–22
–20
–18
–16
–14
–12
–10
–8
–6
–4
FEEDBACK PIN CURRENT (µA)
FEEDBACK PIN CURRENT (AT THRESHOLD)
FEEDBACK PIN VOLTAGE (AT THRESHOLD)
Flyback Blanking TimeShutdown Thresholds
Transconductance of ErrorAmplifier
FREQUENCY (Hz)1k
TRAN
SCON
DUCT
ANCE
(µm
ho)
7000
6000
5000
4000
3000
2000
1000
0
–100010k 100k
1170/1/2 G19
1M 10M
–30
0
30
60
90
120
150
180
210
PHASE (DEG)
θ
gm
7
LT1170/LT1171/LT1172
W
ID AGRABLOCK
1.24V REF
1170/1/2 BD
ERROR AMP
100kHz OSC
2.3V REG
VIN
FB
+
–
+
–
SHUTDOWN CIRCUIT
VC
COMP
LOGIC DRIVER
ANTI- SAT
FLYBACK ERROR
AMP
16VSWITCH
OUT
5A, 75V SWITCH
0.02 (0.04 (0.16
ΩΩ LT1171)Ω LT1172)
0.16ΩCURRENT AMP
GAIN 6≈
0.15V
ALWAYS CONNECT E1 TO THE GROUND PIN ON MINIDIP, 8- AND 16-PIN SURFACE MOUNT PACKAGES. E1 AND E2 INTERNALLY TIED TO GROUND ON TO-3 AND TO-220 PACKAGES.
†
MODE SELECT
E1† E2
(LT1170 AND LT1171 ONLY)
LT1172
OPERATIO
U
The LT1170/LT1171/LT1172 are current mode switchers.This means that switch duty cycle is directly controlled byswitch current rather than by output voltage. Referring tothe block diagram, the switch is turned “on” at the start ofeach oscillator cycle. It is turned “off” when switch currentreaches a predetermined level. Control of output voltage isobtained by using the output of a voltage sensing erroramplifier to set current trip level. This technique hasseveral advantages. First, it has immediate response toinput voltage variations, unlike ordinary switchers whichhave notoriously poor line transient response. Second, itreduces the 90° phase shift at midfrequencies in theenergy storage inductor. This greatly simplifies closed-loop frequency compensation under widely varying inputvoltage or output load conditions. Finally, it allows simplepulse-by-pulse current limiting to provide maximum switch
protection under output overload or short conditions. Alow dropout internal regulator provides a 2.3V supply forall internal circuitry on the LT1170/LT1171/LT1172. Thislow dropout design allows input voltage to vary from 3V to60V with virtually no change in device performance. A100kHz oscillator is the basic clock for all internal timing.It turns “on” the output switch via the logic and drivercircuitry. Special adaptive anti-sat circuitry detects onsetof saturation in the power switch and adjusts drivercurrent instantaneously to limit switch saturation. Thisminimizes driver dissipation and provides very rapid turn-off of the switch.
A 1.2V bandgap reference biases the positive input of theerror amplifier. The negative input is brought out foroutput voltage sensing. This feedback pin has a second
8
LT1170/LT1171/LT1172
OPERATIO
U
function; when pulled low with an external resistor, itprograms the LT1170/LT1171/LT1172 to disconnect themain error amplifier output and connects the output of theflyback amplifier to the comparator input. The LT1170/LT1171/LT1172 will then regulate the value of the flybackpulse with respect to the supply voltage.* This flybackpulse is directly proportional to output voltage in thetraditional transformer coupled flyback topology regula-tor. By regulating the amplitude of the flyback pulse, theoutput voltage can be regulated with no direct connectionbetween input and output. The output is fully floating up tothe breakdown voltage of the transformer windings. Mul-tiple floating outputs are easily obtained with additionalwindings. A special delay network inside the LT1170/LT1171/LT1172 ignores the leakage inductance spike atthe leading edge of the flyback pulse to improve outputregulation.
The error signal developed at the comparator input isbrought out externally. This pin (VC) has four differentfunctions. It is used for frequency compensation, currentlimit adjustment, soft starting, and total regulator shut-down. During normal regulator operation this pin sits at avoltage between 0.9V (low output current) and 2.0V (highoutput current). The error amplifiers are current output(gm) types, so this voltage can be externally clamped foradjusting current limit. Likewise, a capacitor coupledexternal clamp will provide soft start. Switch duty cyclegoes to zero if the VC pin is pulled to ground through adiode, placing the LT1170/LT1171/LT1172 in an idle mode.Pulling the VC pin below 0.15V causes total regulatorshutdown, with only 50µA supply current for shutdowncircuitry biasing. See AN19 for full application details.
Extra Pins on the MiniDIP and Surface Mount Packages
The 8- and 16-pin versions of the LT1172 have theemitters of the power transistor brought out separatelyfrom the ground pin. This eliminates errors due to groundpin voltage drops and allows the user to reduce switchcurrent limit 2:1 by leaving the second emitter (E2) discon-nected. The first emitter (E1) should always be connectedto the ground pin. Note that switch “on” resistance doubleswhen E2 is left open, so efficiency will suffer somewhat
when switch currents exceed 300mA. Also, note that chipdissipation will actually increase with E2 open duringnormal load operation, even though dissipation in currentlimit mode will decrease. See “Thermal Considerations”next.
Thermal Considerations When Using the MiniDIP andSW Packages
The low supply current and high switch efficiency of theLT1172 allow it to be used without a heat sink in mostapplications when the TO-220 or TO-3 package is se-lected. These packages are rated at 50°C/W and 35°C/Wrespectively. The miniDIPs, however, are rated at 100°C/Win ceramic (J) and 130°C/W in plastic (N).
Care should be taken for miniDIP applications to ensurethat the worst case input voltage and load current condi-tions do not cause excessive die temperatures. The follow-ing formulas can be used as a rough guide to calculateLT1172 power dissipation. For more details, the reader isreferred to Application Note 19 (AN19), “Efficiency Calcu-lations” section.
Average supply current (including driver current) is:
IIN ≈ 6mA + ISW(0.004 + DC/40)
ISW = switch currentDC = switch duty cycle
Switch power dissipation is given by:
PSW = (ISW)2 • (RSW)(DC)
RSW = LT1172 switch “on” resistance (1Ω maximum)
Total power dissipation is the sum of supply current timesinput voltage plus switch power:
PD(TOT) = (IIN)(VIN) + PSW
In a typical example, using a boost converter to generate12V at 0.12A from a 5V input, duty cycle is approximately60%, and switch current is about 0.65A, yielding:
IIN = 6mA + 0.65(0.004 + DC/40) = 18mA
PSW = (0.65)2 • (1Ω)(0.6) = 0.25W
PD(TOT) = (5V)(0.018A) + 0.25 = 0.34W
*See note under block diagram.
9
LT1170/LT1171/LT1172
OPERATIO
U
Temperature rise in a plastic miniDIP would be 130°C/Wtimes 0.34W, or approximately 44°C. The maximum am-bient temperature would be limited to 100°C (commercialtemperature limit) minus 44°C, or 56°C.
In most applications, full load current is used to calculatedie temperature. However, if overload conditions mustalso be accounted for, four approaches are possible. First,if loss of regulated output is acceptable under overloadconditions, the internal thermal limit of the LT1172 willprotect the die in most applications by shutting off switchcurrent. Thermal limit is not a tested parameter, however,and should be considered only for noncritical applicationswith temporary overloads. A second approach is to use thelarger TO-220 (T) or TO-3 (K) package which, even withouta heat sink, may limit die temperatures to safe levels underoverload conditions. In critical situations, heat sinking ofthese packages is required; especially if overload condi-tions must be tolerated for extended periods of time.
The third approach for lower current applications is toleave the second switch emitter (miniDIP only) open. Thisincreases switch “on” resistance by 2:1, but reducesswitch current limit by 2:1 also, resulting in a net 2:1reduction in I2R switch dissipation under current limitconditions.
The fourth approach is to clamp the VC pin to a voltage lessthan its internal clamp level of 2V. The LT1172 switchcurrent limit is zero at approximately 1V on the VC pin and2A at 2V on the VC pin. Peak switch current can beexternally clamped between these two levels with a diode.See AN19 for details.
LT1170/LT1171/LT1172 Synchronizing
The LT1170/LT1171/LT1172 can be externally synchro-nized in the frequency range of 120kHz to 160kHz. This isaccomplished as shown in the accompanying figures.Synchronizing occurs when the VC pin is pulled to groundwith an external transistor. To avoid disturbing the DCcharacteristics of the internal error amplifier, the width ofthe synchronizing pulse should be under 0.3µs. C2 setsthe pulse width at ≅ 0.2µs. The effect of a synchronizingpulse on the LT1170/LT1171/LT1172 amplifier offset canbe calculated from:
KT = 26mV at 25°C qtS = pulse widthfS = pulse frequencyIC = VC source current (≈200µA)VC = operating VC voltage (1V to 2V)R3 = resistor used to set mid-frequency “zero” in frequency compensation network.
With tS = 0.2µs, fS = 150kHz, VC = 1.5V, and R3 = 2k, offsetvoltage shift is ≈3.8mV. This is not particularly bother-some, but note that high offsets could result if R3 werereduced to a much lower value. Also, the synchronizingtransistor must sink higher currents with low values of R3,so larger drives may have to be used. The transistor mustbe capable of pulling the VC pin to within 200mV of groundto ensure synchronizing.
1170/1/2 OP02
D1 1N4158
R2 2.2k
LT1170
GND
VIN
VC
C1
R3
FROM 5V LOGIC
C2 100pF
D2 1N4158
* SILICONIX OR EQUIVALENT
VN2222*
1170/1/2 OP01
C2 39pF R1
3k
R2 2.2k
LT1170
GND
VIN
VC
C1
R32N2369
FROM 5V LOGIC
Synchronizing with Bipolar TransistorSynchronizing with MOS Transistor
∆V
KTq
t f I VR
IOS
S S CC
C=
( )( ) +
3
10
LT1170/LT1171/LT1172
U
SA
O
PPLICATITYPICAL
Flyback Converter
LCD Contrast Supply
1170/1/2 TA03
D1
C1 2000µF
+C4* 100µF
C2 0.15µF
R1 3.74k
R2 1.24k
VIN 20V TO 30V
R3 1.5k
*REQUIRED IF INPUT LEADS ≥ 2"
LT1170
VINVSW
FBVC
OPTIONAL FILTER
L2 5µH
C4 100µF
+
VOUT 5V 6A
VSNUB
CLAMP TURN-ON SPIKE
PRIMARY FLYBACK VOLTAGE =
LT1170 SWITCH VOLTAGE AREA “a” = AREA “b” TO MAINTAIN ZERO DC VOLTS ACROSS PRIMARY SECONDARY VOLTAGE AREA “c” = AREA “d” TO MAINTAIN ZERO DC VOLTS ACROSS SECONDARY PRIMARY CURRENT SECONDARY CURRENT LT1170 SWITCH CURRENT SNUBBER DIODE CURRENT
VOUT + Vf N
0V
VINa
b
0Vc
d
VOUT + Vf
N • VIN
∆I IPRI
0IPRI/N
IPRI
IPRI
t = (IPRI)(LL)
VSNUB
0
0
0
1
N* = 1/3
N*D3 25V 1W
D2 MUR110
GND
C4 0.047µF
VOUT –10V TO –26V
1170/1/2 TA04
R3 15kOPTIONAL
SHUTDOWN
R2 100k
R1 200k
C1 1µF TANTALUM
D1 1N914
C3 0.0047µF
C2*** 2µF TANTALUM
D2
VN2222
5V* L1** 50µH
VBAT* 3V TO 20V
+
+
VIN
VC
FB
VSW
LT1172
E2
E1GND
D3
*
**
***
D2, D3 = ER82.004 600mA SCHOTTKY. OTHER FAST SWITCHING TYPES MAY BE USED.
VIN AND BATTERY MAY BE TIED TOGETHER. MAXIMUM VALUE FOR VBAT IS EQUAL TO THE NEGATIVE OUTPUT + 1V. WITH HIGHER BATTERY VOLTAGES, HIGHEST EFFICIENCY IS OBTAINED BY RUNNING THE LT1172 VIN PIN FROM 5V. SHUTTING OFF THE 5V SUPPLY WILL AUTOMATICALLY TURN OFF THE LT1172. EFFICIENCY IS ABOUT 80% AT IOUT = 25mA.
R1, R2, R3 ARE MADE LARGE TO MINIMIZE BATTERY DRAIN IN SHUTDOWN, WHICH IS APPROXIMATELY VBAT /(R1 + R2 + R3).
FOR HIGH EFFICIENCY, L1 SHOULD BE MADE ON A FERRITE OR MOLYPERMALLOY CORE. PEAK INDUCTOR CURRENTS ARE ABOUT 600mA AT POUT = 0.7Ω. INDUCTOR SERIES RESISTANCE SHOULD BE LESS THAN 0.4Ω FOR HIGH EFFICIENCY.
OUTPUT RIPPLE IS ABOUT 200mVP-P TO 400mVP-P WITH C2 = 2µF TANTALUM. IF LOWER RIPPLE IS DESIRED, INCREASE C2, OR ADD A 10Ω , 1µF TANTALUM OUTPUT FILTER.
11
LT1170/LT1171/LT1172
Negative-to-Positive Buck-Boost Converter†
Driving High Voltage FET(for Off-Line Applications, See AN25)
1170/1/2 TA05
VINVSW
LT1170
GND
10V TO 20V
D1
+
DGQ1
U
SA
O
PPLICATITYPICAL (Note that maximum output currents are divided by 2 for LT1171, by 4 for LT1172.)
Negative Buck Converter
C4* 100µF
VOUT 12V 2A
1170/1/2 TA07
R3 2.2k
C2 1000µF
D1
C1 0.22µF
Q1
++
VIN
VCFB
VSW
LT1170
GNDOPTIONAL
INPUT FILTER
L3
VIN –20V
REQUIRED IF INPUT LEADS ≥ 2" PULSE ENGINEERING 92114, COILTRONICS 50-2-52
* **
R2 1.24k
L1** 50µH
OPTIONAL OUTPUT FILTER
C3
L2
R1 11.3k
THIS CIRCUIT IS OFTEN USED TO CONVERT –48V TO 5V. TO GUARANTEE FULL SHORT-CIRCUIT PROTECTION, THE CURRENT LIMIT CIRCUIT SHOWN IN AN19, FIGURE 39, SHOULD BE ADDED WITH C1 REDUCED TO 200pF.
†
C3* 100µF
–5.2V 4.5A
1170/1/2 TA09
R3
L1** 50µH
R1 4.64k
C2 1000µFD1
C1
Q1 2N3906
+
VIN
VC
FB
VSW
LT1170
GNDOPTIONAL
INPUT FILTER
L3
VIN –20V
LOAD
REQUIRED IF INPUT LEADS ≥ 2" PULSE ENGINEERING 92114 COILTRONICS 50-2-52
* **
R2 1.24k
+
R4 12k
L2 4µH
OPTIONAL OUTPUT FILTER
C4 200µF
+
External Current Limit
External Current Limit
1170/1/2 TA06
VX
D1
LT1170
GND
R2
≈ 2VVC
R1 500Ω
1170/1/2 TA08
R2
C2
VIN
VCFB
VSW
LT1170
GNDVIN
NOTE THAT THE LT1170 GND PIN IS NO LONGER COMMON TO VIN
–.
R1 1k
+
–
C1 1000pF
Q1
RS
12
LT1170/LT1171/LT1172
U
SA
O
PPLICATITYPICALPositive-to-Negative Buck-Boost Converter
High Efficiency Constant Current Charger
D2 MBR340
1170/1/2 TA11
+
INPUT VOLTAGE > VBAT + 2V < 35V
C2 2.2µF
35V TANTALUM
R7 22k
R8 1k
C3 0.47µF
V+
V–R4 1k
C4 200µF 25V BATTERY
2V TO 25V
L2* 10µH, 1A
L1 100µH, 1A
R5 0.05Ω
R3 25k
R2 1k
RUN = 0V SHUTDOWN = 5V
* L2 REDUCES RIPPLE CURRENT INTO THE BATTERY BY ABOUT 20:1. IT MAY BE OMITTED IF DESIRED.
I = 1.244V • R4 R3 • R5
= 1A AS SHOWNCHRG
+
R6 78k
VINCV
FB
VSW
GND
D1 1N5819
C4 0.01µF
LT1006
+
–
+
LT1171
C1 200µF
35V
+
1A2N3904
+
GND
2µF1170/1/2 TA12
D1 1N914
33pF 3kV
10µF TANT
R3 10k
50k INTENSITY
ADJUST
1N5818L1**
300µH
INPUT VOLTAGE† 4.5V TO 20V
Q1,Q2 = BCP56 OR MPS650/561 COILTRONICS CTX300-4 SUMIDA 6345-020 OR COILTRONICS 110092-1 A MODIFICATION WILL ALLOW OPERATION DOWN TO 4.5V. CONSULT FACTORY.
* **
***
†
C6 1 Fµ
R1 560Ω
1k
LT1172
INV
VC
VSWE2
E1
D2 1N914
LAMP
FB
L2***
0.02µF
A
B
Q1*
+
+
Q2*
C4 1µF
VIN 10V TO 30V
1170/1/2 TA10
R3 5k
C5 100µF*
D3†
1N4001
C2 0.1µF
+
+
VIN
VCFB
VSW
LT1170
GND
VOUT –12V 2A
REQUIRED IF INPUT LEADS ≥ 2" PULSE ENGINEERING 92114, COILTRONICS 50-2-52
* **
R2 1.24k
L1** 50µH
R5†
470Ω, 1W
TO AVOID STARTUP PROBLEMS FOR INPUT VOLTAGES BELOW 10V, CONNECT ANODE OF D3 TO VIN, AND REMOVE R5. C1 MAY BE REDUCED FOR LOWER OUTPUT CURRENTS. C1 ≈ (500µF)(IOUT). FOR 5V OUTPUTS, REDUCE R3 TO 1.5k, INCREASE C2 TO 0.3µF, AND REDUCE R6 TO 100Ω.
†
C3 2µF
+
D2
1N914 R4
47Ω
+C1†
1000µF
D1
R6 470Ω
R1
10.7k
Backlight CCFL Supply (see AN45 for details)
13
LT1170/LT1171/LT1172
U
SA
O
PPLICATITYPICALPositive Buck Converter
Forward Converter
Negative Boost Regulator Driving High Voltage NPN
C5* 100µF
VIN
1170/1/2 TA13
R3 470Ω
5V, 4.5A
D2 1N914
C1 1µF
+
+
VIN
VCFB
VSW
LT1170
GND
REQUIRED IF INPUT LEADS ≥ 2" PULSE ENGINEERING 92114 COILTRONICS 50-2-52
* **
R1 3.74k
L1** 50µH
R4 10Ω
–
+C3
2.2µF
D1
r
R2 1.24k
C2 1µF
–
+C4
1000µF100mA MINIMUM
D3
OPTIONAL OUTPUT FILTER
C5 200µF
L2 4µH
1170/1/2 TA16
C1 2000µF
+
C3
R4
R2 1.24k
VIN 20V TO 30V
R3
LT1170
VINVSW
FBVC
1 N
D3
L1 25µH
C4
R6 330Ω
R5 1Ω
C2 M
D2
D1VOUT 5V, 6A
T1
Q1
D4
R1 3.74k
GND
1170/1/2 TA15
D2
C1
SETS IB (ON) SETS IB (OFF)
* **
R2**
VIN
VSW
LT1170
GND
D1
Q1R1*
C4* 470µF
1170/1/2 TA14
R3 3.3k
C3 10µF
D1C2 0.22µF
+
VIN
VC
FB
LT1170
GND
VIN –15V
REQUIRED IF INPUT LEADS ≥ 2"*
R2 1.24k
D2
R1 27k
VSW
–
+
L1 50µH
C1 1000µF
+ RO (MINIMUM LOAD)
VOUT –28V, 1A
14
LT1170/LT1171/LT1172
U
SA
O
PPLICATITYPICAL
Positive Current Boosted Buck Converter
High Efficiency 5V Buck Converter
1170/1/2 TA18
C1 0.33µF
470Ω 2W
R7 1k
VIN 28V
R3 680Ω
LT1170
VINVSW
FBVC
1: ND2
R2 1.24k
C3 0.47µF
D1
VOUT 5V, 10A
N ≈ 0.25
R4 1.24k
GND
+C5* 100µF
R6 470Ω
C6 0.002µF
–
+
C4 0.01µF
7
VIN
6
4
8200pF
2
3R5 5k
R1 5k +C2
5000µF
* REQUIRED IF INPUT LEADS ≥ 2"
V+
V– LM308 COMP
+
VSW
FBGND
VIN
VC
LT1170
+C1 330µF 35V
C6 0.02µF
C4 0.1µF
R1 680Ω
C5 0.03µF
D1 MBR330p
C3 4.7µF TANT
D2 1N4148
L1 50µH R2*
0.013Ω
C2 390µF 16V
VOUT 5V 3A**
+
×
MODE LOGIC 220pF
<0.3V = NORMAL MODE >2.5V = SHUTDOWN OPEN = BURST MODE
* R2 IS MADE FROM PC BOARD COPPER TRACES. ** MAXIMUM CURRENT IS DETERMINED BY THE CHOICE OF LT1070 FAMILY. SEE APPLICATION SECTION.
VIN
1170/1/2 TA17
OPTIONAL OUTPUT FILTER
100µF 16V
10µH 3A
+
VC
GND
MODE
DIODE
VOUT
VLIM
V+
LT1432VIN
15
LT1170/LT1171/LT1172
U
PACKAGE DESCRIPTIO Dimensions in inches (millimeters) unless otherwise noted.
J8 Package8-Lead CERDIP (Narrow 0.300, Hermetic)
(LTC DWG # 05-08-1110)
J8 0694
0.014 – 0.026 (0.360 – 0.660)
0.200 (5.080)
MAX
0.015 – 0.060 (0.381 – 1.524)
0.125 3.175 MIN0.100 ± 0.010
(2.540 ± 0.254)
0.300 BSC (0.762 BSC)
0.008 – 0.018 (0.203 – 0.457)
0° – 15°
0.385 ± 0.025 (9.779 ± 0.635)
0.005 (0.127)
MIN
0.405 (10.287)
MAX
0.220 – 0.310 (5.588 – 7.874)
1 2 3 4
8 7 6 5
0.025 (0.635)
RAD TYP0.045 – 0.068
(1.143 – 1.727) FULL LEAD
OPTION
0.023 – 0.045 (0.584 – 1.143)
HALF LEAD OPTION
CORNER LEADS OPTION (4 PLCS)
0.045 – 0.068 (1.143 – 1.727)
NOTE: LEAD DIMENSIONS APPLY TO SOLDER DIP/PLATE OR TIN PLATE LEADS.
16
LT1170/LT1171/LT1172
U
PACKAGE DESCRIPTIO Dimensions in inches (millimeters) unless otherwise noted.
K Package4-Lead TO-3 Metal Can(LTC DWG # 05-08-1311)
K4(TO-3) 0695
72°18°
0.495 – 0.525 (12.57 – 13.34)
R
0.470 TP P.C.D.
0.167 – 0.177 (4.24 – 4.49)
R
0.151 – 0.161 (3.84 – 4.09)
DIA 2 PLC
0.655 – 0.675 (16.64 – 19.05)
1.177 – 1.197 (29.90 – 30.40)
0.038 – 0.043 (0.965 – 1.09)
0.060 – 0.135 (1.524 – 3.429)
0.320 – 0.350 (8.13 – 8.89)
0.420 – 0.480 (10.67 – 12.19)
0.760 – 0.775 (19.30 – 19.69)
17
LT1170/LT1171/LT1172
N8 Package8-Lead PDIP (Narrow 0.300)
(LTC DWG # 05-08-1510)
U
PACKAGE DESCRIPTIO Dimensions in inches (millimeters) unless otherwise noted.
N8 0695
0.005 (0.127)
MIN
0.100 ± 0.010 (2.540 ± 0.254)
0.065 (1.651)
TYP
0.045 – 0.065 (1.143 – 1.651)
0.130 ± 0.005 (3.302 ± 0.127)
0.015 (0.380)
MIN
0.018 ± 0.003 (0.457 ± 0.076)
0.125 (3.175)
MIN
1 2 3 4
8 7 6 5
0.255 ± 0.015* (6.477 ± 0.381)
0.400* (10.160)
MAX
0.009 – 0.015 (0.229 – 0.381)
0.300 – 0.325 (7.620 – 8.255)
0.325+0.025 –0.015+0.635 –0.3818.255( )
*THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.010 INCH (0.254mm)
18
LT1170/LT1171/LT1172
U
PACKAGE DESCRIPTIO Dimensions in inches (millimeters) unless otherwise noted.
Q Package5-Lead Plastic DD Pak (LTC DWG # 05-08-1461)
Q(DD5) 0396
0.028 – 0.038 (0.711 – 0.965)
0.143+0.012 –0.020
( )3.632+0.305 –0.508
0.057 – 0.077 (1.447 – 1.955) 0.013 – 0.023
(0.330 – 0.584)
0.095 – 0.115 (2.413 – 2.921)
0.004+0.008 –0.004
( )0.102+0.203 –0.102
0.050 ± 0.012 (1.270 ± 0.305)
0.059 (1.499)
TYP
0.045 – 0.055 (1.143 – 1.397)
0.165 – 0.180 (4.191 – 4.572)
0.330 – 0.370 (8.382 – 9.398)
0.060 (1.524)
TYP0.390 – 0.415
(9.906 – 10.541)
15° TYP
0.300 (7.620)
0.075 (1.905)
0.183 (4.648)
0.060 (1.524)
0.060 (1.524)
0.256 (6.502)
BOTTOM VIEW OF DD PAK HATCHED AREA IS SOLDER PLATED
COPPER HEAT SINK
S8 Package8-Lead Plastic Small Outline (Narrow 0.150)
(LTC DWG # 05-08-1610)
1 2 3 4
0.150 – 0.157** (3.810 – 3.988)
8 7 6 5
0.189 – 0.197* (4.801 – 5.004)
0.228 – 0.244 (5.791 – 6.197)
0.016 – 0.050 0.406 – 1.270
0.010 – 0.020 (0.254 – 0.508)
× 45°
0°– 8° TYP0.008 – 0.010
(0.203 – 0.254)
SO8 0695
0.053 – 0.069 (1.346 – 1.752)
0.014 – 0.019 (0.355 – 0.483)
0.004 – 0.010 (0.101 – 0.254)
0.050 (1.270)
BSCDIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE
*
**
19
LT1170/LT1171/LT1172
U
PACKAGE DESCRIPTIO Dimensions in inches (millimeters) unless otherwise noted.
SW Package16-Lead Plastic Small Outline (Wide 0.300)
(LTC DWG # 05-08-1620)
S16 (WIDE) 0396
NOTE 1
0.398 – 0.413* (10.109 – 10.490)
16 15 14 13 12 11 10 9
1 2 3 4 5 6 7 8
0.394 – 0.419 (10.007 – 10.643)
0.037 – 0.045 (0.940 – 1.143)
0.004 – 0.012 (0.102 – 0.305)
0.093 – 0.104 (2.362 – 2.642)
0.050 (1.270)
TYP0.014 – 0.019
(0.356 – 0.482) TYP
0° – 8° TYP
NOTE 10.009 – 0.013
(0.229 – 0.330)0.016 – 0.050
(0.406 – 1.270)
0.291 – 0.299** (7.391 – 7.595)
× 45°0.010 – 0.029 (0.254 – 0.737)
NOTE: 1. PIN 1 IDENT, NOTCH ON TOP AND CAVITIES ON THE BOTTOM OF PACKAGES ARE THE MANUFACTURING OPTIONS. THE PART MAY BE SUPPLIED WITH OR WITHOUT ANY OF THE OPTIONS
DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE
* **
20
LT1170/LT1171/LT1172
LINEAR TECHNOLOGY CORPORATION 1991
117012fd LT/GP 1097 4K REV D • PRINTED IN USA
U
PACKAGE DESCRIPTIO Dimensions in inches (millimeters) unless otherwise noted.
T Package3-Lead Plastic TO-220(LTC DWG # 05-08-1420)
T5 (TO-220) 0694
0.028 – 0.038 (0.711 – 0.965)
0.057 – 0.077 (1.448 – 1.956)
0.135 – 0.165 (3.429 – 4.191)
0.700 – 0.728 (17.780 – 18.491)
0.045 – 0.055 (1.143 – 1.397)
0.095 – 0.115 (2.413 – 2.921)
0.013 – 0.023 (0.330 – 0.584)
0.620 (15.75)
TYP
0.155 – 0.195 (3.937 – 4.953)
0.152 – 0.202 (3.860 – 5.130)
0.260 – 0.320
(6.604 – 8.128)
0.165 – 0.180 (4.293 – 4.572)
0.147 – 0.155 (3.734 – 3.937)
DIA
0.390 – 0.415 (9.906 – 10.541)
0.330 – 0.370 (8.382 – 9.398)
0.460 – 0.500 (11.684 – 12.700)
0.570 – 0.620 (14.478 – 15.748)
0.230 – 0.270 (5.842 – 6.858)
Linear Technology Corporation1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900FAX: (408) 434-0507 TELEX: 499-3977 www.linear-tech.com
PART NUMBER DESCRIPTION COMMENTS
LT1070/LT1071/LT1072 5A/2.5A/1.25A High Efficiency Switching Regulators 40kHz, VIN to 60V, VSW to 75V
LT1074/LT1076 5.5A/2A Step-Down Switching Regulators 100kHz, Also for Positive-to-Negative Conversion
LT1082 1A, High Voltage, High Efficiency Switching Regulator VIN to 75V, VSW to 100V, Telecom
LT1268/LT1268B 7.5A, 150kHz Switching Regulators VIN to 30V, VSW to 60V
LT1269/LT1271 4A High Efficiency Switching Regulators 100kHz/60kHz, VIN to 30V, VSW to 60V
LT1270/LT1270A 8A and 10A High Efficiency Switching Regulators 60kHz, VIN to 30V, VSW to 60V
LT1370 500kHz High Efficiency 6A Switching Regulator High Power Boost, Flyback, SEPIC
LT1371 500kHz High Efficiency 3A Switching Regulator Good for Boost, Flyback, Inverting, SEPIC
LT1372/LT1377 500kHz and 1MHz High Efficiency 1.5A Switching Regulators Directly Regulates ±VOUT
LT1373 250kHz Low Supply Current High Efficiency 1.5A Switching Regulator Low 1mA Quiescent Current
LT1374 4A, 500kHz Step-Down Switching Regulator Synchronizable, VIN to 25V
LT1375/LT1376 1.5A, 500kHz Step-Down Switching Regulators Up to 1.25A Out from an SO-8
LT1425 Isolated Flyback Switching Regulator 6W Output, ±5% Regulation,No Optocoupler Needed
LT1507 500kHz Monolithic Buck Mode Switching Regulator 1.5A Switch, Good for 5V to 3.3V
LT1533 Ultralow Noise 1A Switching Regulator Push-Pull, <100µVP-P Output Noise
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